St. Paul had stepped up targeted enforcement of its housing codes in distressed neighborhoods in an effort to crack down on unsafe conditions, like rat infestations. Those sweeps often forced landlords to make expensive repairs, and the landlords sued, with a novel complaint. They said that the effect of the city's action was discriminatory because it could lead to a reduction in affordable housing in the city, which would disproportionately affect African-Americans and other minorities. In so doing, they relied on a long-standing tool the Justice Department has used in housing discrimination cases: the principle that an action need not be discriminatory in intent but merely in effect to be illegal. By the time the case was headed for the Supreme Court, civil rights groups, housing advocates, Walter Mondale and the Justice Department urged the city to drop the case for fear that the high court would use the occasion to overturn that principle, which was never the city's intent. Instead, it is now poised to fight the issue on its merits in federal district court.